In 3.5.x there is no easy way of changing the membership config using rolling restarts because of the introduction of dynamic reconfig feature in
ZOOKEEPER-107, which automatically manages membership configuration parameters. ZOOKEEPER-2014 introduced a reconfigEnabled flag to turn on / off the reconfig feature. We can use same flag and when it sets to false, it should disable both in memory and on disk updates of membership configuration information, besides disabling the reconfig commands on CLI which ZOOKEEPER-2014 already did, so users can continue using rolling restarts if needed.
We should also document explicitly the support of membership changes via rolling restarts will be deprecated at what release time frame and promote reconfig as the replacement.
The problem was raised at user mailing list by Guillermo Vega-Toro, reference thread:
|Update documentation on how to do rolling restart||Open|
|Test case improvement||Open||Unassigned|
|Update documents on getConfig when reconfig is disabled.||Open||Unassigned|